Circadian rhythms and the gut microbiome in the fruit fly, Drosophila melanogaster

Abstract

Circadian rhythms (CRs) are 24-hour oscillations of physiological rhythms that regulate behavior, physiology, and metabolism in many organisms. CRs originate within an organism and are established via regular exposure to recurring stimuli such as sunlight. All organisms with an intestinal tract harbor a community of bacteria called the commensal gut microbiome (GM). The GM is largely influenced by the host CR and has been shown to cycle in mammals. Also, the GM has been shown to impact the expression of host circadian clock genes in mammals. These host-gut interactions have not been extensively studied in non-mammals. In our study, we documented the cycling of the GM and its impact on the host CR in the fruit fly, Drosophila melanogaster. To study the cycling of the GM, the guts of flies with a functional and non-functional circadian clock were wholly dissected out to examine rhythmic changes in taxa. To examine GM impact on the host CR, flies with and without a GM were examined for food-seeking behavior. We found that taxa in both genotypes cycled, but more taxa cycled in functional CR hosts than in nonfunctional, potentially indicating the host clock is not the only driver of rhythmicity. We also found that flies with and without a GM have differing time-of-day feeding preference, which may indicate the gut microbiome impacts the host CR to some degree.